Field of Technology
The embodiments herein relate to a display device, and more particularly, to a display device with an integrated in-cell type touch screen and a driving method thereof.
Discussion of the Related Art
Touch screens are a type of input device that are included in display devices such as liquid crystal display (LCD) devices, field emission displays (FEDs), plasma display panels (PDPs), electroluminescent displays (ELDs), and electrophoretic displays (EPDs), and enables a user to input information by directly touching a screen with a finger, a pen or the like while looking at the screen of the display device.
Particularly, the demand for display devices with an integrated in-cell type touch screen, which include a plurality of built-in elements configuring the touch screen for slimming portable terminals such as smart phones and tablet personal computers (PCs), is increasing.
In a related art display device with integrated in-cell type touch screen disclosed in U.S. Pat. No. 7,859,521, a plurality of common electrodes for display are segmented into a plurality of touch driving areas and touch sensing areas, thereby allowing a mutual capacitance to be generated between the touch driving area and the touch sensing area. Therefore, the related art display device measures a mutual capacitance change that occurs in touch, and thus determines whether there is a touch.
In the display device with an integrated in-cell type touch screen, a driving pulse is applied to common electrodes corresponding to a touch driving area when a panel operates in a touch driving mode in order for each of the common electrodes to perform a function of a touch electrode.
In this case, as a distance between a touch electrode and a circuit unit which applies the driving pulse to the touch electrode increases, the driving pulse is delayed, and for this reason, a time constant of the driving pulse increases, and a charging rate based on the driving pulse is reduced. As a result, as the distance between the touch electrode and the circuit unit increases, a level of a touch signal which is detected in a sensing area is reduced, and for this reason, a reduction and deviation of touch performance occur in each touch driving area.